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The pallid sturgeon (Scaphirhynchus albus) is an endangered fish of the Missouri River. The Missouri River Pallid Sturgeon Effects Analysis set out to judge how managing the river has affected the sturgeon, and how future management might.
What an effects analysis is
The idea is practical and simple. An effects analysis combines three things to better understand an endangered species and how to help it:
- gathering reliable scientific information;
- critically assessing and combining the available data and analyses;
- analysing how management actions affect the species and its habitat.
It grew out of the recognition that the Missouri River Recovery Program would benefit from a thorough, updated look at what is known, what is not, and what needs to be known to act effectively. The core team — sturgeon and river experts from the U.S. Geological Survey, the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service and Mississippi State University — drew on reviews by state agencies and universities.
The reports
Three foundation reports (2015–2016) compiled the available information and models, built conceptual ecological models of how river management links to sturgeon populations, and filtered the hundreds of resulting hypotheses — using expert surveys and existing evidence — down to 21 working management hypotheses. An integrative report (Jacobson and others, 2016) assessed those 21; seven outside experts and the Missouri River Recovery Implementation Committee's Independent Science Advisory Panel peer-reviewed it. It is meant as the first in a series of updates supporting adaptive management.
The analysis covers the Upper Missouri from Fort Peck Dam in Montana to the head of Lake Sakakawea, the Yellowstone River above its confluence with the Missouri, and the Lower Missouri from Gavins Point Dam to the Mississippi at St. Louis — plus possibly some of the Mississippi below and tributaries the sturgeon may use.
The geographic scope of the effects analysis: the segments studied (dark red) and possible extensions (pink). USGS.
The 21 hypotheses
| Where and what | Hypotheses | Where it stands |
|---|---|---|
| Fort Peck Dam: change the flow regime | natural flows for food and energy; spring pulses to cue gathering and spawning; lower spring flows to reduce the drift of young fish (1–3) | theoretical support but too little data to forecast; research and possible pulse experiments |
| Fort Peck Dam: temperature control | warmer water for productivity and for growth with less drift (4–5) | research |
| Fort Peck Dam: add sediment | more turbidity, less predation (6) | laboratory data equivocal; research on predation of eggs and embryos |
| Yellowstone River: passage at Intake Diversion Dam | longer potential dispersal (7) | implementation likely, with monitoring |
| Upper basin: hatchery stocking | better size classes; genetic diversity and viability (8–9) | implemented; validate with monitoring |
| Lake Sakakawea: drawdown | longer potential drift distance (10) | potentially effective; research on anoxia and drift |
| Gavins Point Dam: change the flow regime | spring pulses; natural flows for productivity and energy; lower spring flows (11–14) | theoretical support, data inadequate or equivocal; research and possible pulse experiments |
| Gavins Point Dam: temperature | natural temperatures to cue spawning (15) | research and monitoring |
| Lower Missouri: reshape the channel | habitats for spawning, food production, foraging and intercepting drifting young (16–19) | partly implemented; field experiments and monitoring |
| Lower basin: hatchery stocking | better size classes; parentage and fitness (20–21) | implemented; validate with monitoring |
The key finding: what we don't know
The analysis revealed how much about the pallid sturgeon's biology is uncertain. Basic gaps make it hard to say how a management action will change the population — not for lack of effort: two decades of research have produced a substantial body of science. The challenge is studying a very rare fish that lives in a deep, fast, muddy river where it can hardly be watched.
Even so, the team was asked to build the best available models to guide decisions and weigh costs and benefits. A modelling framework still helps structure hypotheses, test how sensitive the population is to management, set research priorities and make sense of monitoring data. For some hypotheses the evidence is only theory, rare datasets or expert opinion. But useful simulation models now predict how management affects the survival of drifting free embryos in the Upper Missouri and Lower Yellowstone, and how flow and channel changes affect habitat in the Lower Missouri; a population model tests sensitivity to the survival of each life stage, stocking choices and other scenarios.
The level of uncertainty and risk for each hypothesis suggests whether to implement it fully, test it as a field experiment, or research it further. Understanding the sturgeon's reproduction will take laboratory and field work together: field results are most convincing, but some stages of its life cannot be seen in the field.
Adaptive management
These uncertainties point to adaptive management: actions designed as learning experiments, with new information used to improve decisions, and even hypotheses set aside early brought back when new observations call for them. A continuing effects analysis can keep turning science into information that decision makers can use.
Sources
- Robert B. Jacobson, The Missouri River Scaphirhynchus albus (Pallid Sturgeon) Effects Analysis, USGS Fact Sheet 2016–3057, prepared with the Missouri River Recovery Program. https://doi.org/10.3133/fs20163057
- Integrative report: R. B. Jacobson and others, USGS Scientific Investigations Report 2016–5064. http://dx.doi.org/10.3133/sir20165064
Licencia: CC0 1.0 (dominio público) · Adaptado de pubs.usgs.gov
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